Haley also confirmed that new sanctions against Russia will be announced on Monday.

US will not pull its troops out of Syria until Washington's goals are accomplished, Nikki Haley, the US Ambassador to the United Nations said.

According to Haley, the three aims for the US are ensuring chemical weapons are not used in any way that pose a risk to US interests; Islamic State of Iraq and the Levant (ISIL, also known as ISIS) is defeated; and there is a good vantage point to watch what Iran is doing.

The attack came a week after a suspected deadly chemical attack on the rebel-held Damascus suburb of Douma.

The White Helmets, a local civil defence agency, accused the Assad government of carrying out the gas attack, which is believed to have killed 85 civilians, including children, and injured hundreds of others.

The US and allies say they have evidence that the attack was carried out by Assad's forces.

In response, Russia pledged to retaliate for what it described as a "fabricated" chemical gas attack.